This invention relates generally to medical electrical stimulators, more particularly to muscle stimulators for functional electrical stimulation, and most particularly to implantable electrical stimulators for stimulation of muscle employed as a myocardial substitute.
U.S. Pat. No. 4,735,205 issued to Chachques et al discloses method and apparatus for employing the latissimus dorsi muscle to assist cardiac function. This patent is incorporated herein by reference in its entirety. In the method disclosed in this patent, the latissimus dorsi muscle is surgically resected, divided into two parts to cover the surface of the heart, and inserted into the thoracic cavity by means of a resection of the second rib. After or before positioning the muscle, stimulating electrodes are threaded into the muscle at desired locations to affect contraction of the muscle. Stimulating pulses are provided by an implanted pulse generator, preferably implanted subcutaneously in the abdomen. A pulse generator appropriate for such use is disclosed in U.S. Pat. No. 4,411,268 issued to Cox. Timing of contractions of the latissimus dorsi muscle is controlled by the stimulator, which senses natural contractions of the heart, and stimulates the latissimus dorsi muscle to contract in synchrony therewith. Sensing of heart activity, and stimulation of heart contractions in the absence of underlying heart activity is accomplished by means of an additional electrical lead, coupling the heart to the pulse generator.
The pulse generator disclosed in the above cited patent, like most implantable pulse generators, has a generally flattened external configuration with two major, generally planar surfaces and a circumferential edge surface. Mounted to the circumferential edge surface is a connector block which includes receptacles for each of the three illustrated stimulation leads. This pulse generator is implanted with its major surfaces generally parallel to the skin.